What are the materials of plastic bags?


Release time:

2021-09-30

Polyethylene (PE), referred to as PE. It is a high-molecular organic compound formed by addition polymerization of ethylene. Polyethylene is recognized as a good material in contact with food in the world. It is non-toxic, tasteless and odorless, and meets food packaging hygiene standards. Polyethylene film, light and transparent, has the properties of moisture resistance, oxygen resistance, acid resistance, alkali resistance, general air tightness, and excellent heat sealability. Known as the "flower of plastic". It is the most important and most important material for plastic packaging printing.

1. Polyethylene (PE), referred to as PE. It is a high-molecular organic compound formed by addition polymerization of ethylene. Polyethylene is recognized as a good material in contact with food in the world. It is non-toxic, tasteless and odorless, and meets food packaging hygiene standards. Polyethylene film, light and transparent, has the properties of moisture resistance, oxygen resistance, acid resistance, alkali resistance, general air tightness, and excellent heat sealability. Known as the "flower of plastic". It is the most important and most important material for plastic packaging printing.

2. Polyvinyl chloride is abbreviated as PVC, and its molecular formula is (CH2—CH2CL)n. It is the most important type of vinyl polymer and is currently the world's second largest plastic product after polyethylene. Domestic production ranks first among plastics. In the printing industry, polyvinyl chloride color calendered film and transparent glazing film are often used to make the packaging and decoration of books, folders, tickets and other covers.

3. Shrinkfilm is a kind of thermoplastic film that is stretched and oriented during the production process, and shrinks when it is subjected to hot air treatment or infrared radiation during use. After the heat treatment, the film is tightly wrapped on the packaging, the shrinkage force reaches a large value in the cooling stage, and can be stored for a long time.

4. Low-density polyethylene, or LDPE for short, is the most used variety in the plastic packaging and printing industries in various countries. The specific gravity is 0.92~0.93, and it can float on water. Low crystallinity (60%), bulk polymerization is carried out at a pressure of 1000~3000kg/cm2, so it is also called high pressure polyethylene. At 23°C, the density is around 0.92. The calendering formability is poor, and it can be processed into a tubular film by the blow molding method. Suitable for food packaging, fiber product packaging, and daily chemical products packaging.

5. High-density polyethylene, referred to as HDPE. The density is 0.941~0.965g/cubic centimeter. It is polymerized by low pressure, so it is also called low pressure polyethylene. It is milky white, indicating poor gloss. The film can be processed by blow molding and T-die extrusion processes. It is heat-resistant and steam-boiled, cold-resistant and freeze-resistant, has good moisture-proof, gas-proof and insulating properties, and is not easy to be damaged. Its strength is twice that of LDPE. Very easy to speak. It has strong paper-like properties and is known as "paper-like plastic film".

6. Biaxially stretched polypropylene film, also called biaxially stretched polypropylene film, the English abbreviation code BOPP, which is characterized by the orientation of stretched molecules, mechanical strength, folding strength, air density, and moisture barrier are better than ordinary plastic films . Compared with cellophane per unit area, the unit price is lower than that of cellophane. Because of the excellent transparency of this kind of film, the reproduced color after printing is extraordinarily bright and beautiful, and it is an important base material for plastic composite flexible packaging.